Patent GB-796224-A (GB)
Title: Equipment for determining the distribution of cargo in an aircraft to achieve a desired centre of gravity
IPC: G06G7/70
Filed: 1954-08-20
Abstract: 796,224. Electric analogue calculating systems. CONTINENTAL SILVER CO., Inc. Aug. 20, 1954 [Sept. 11, 1953], No. 24330/54. Class 37. [Also in Group XXXVII] General.- Equipment for determining the distribution of cargo of a given weight in an aircraft having main wheels and an additional wheel so as to obtain a desired centre of gravity for the loaded aircraft comprises a control circuit including a first variable electrical impedance unit, a weight determining apparatus responsive to each aircraft wheel and controlling for each wheel an electrical impedance unit of value proportional to the weight resting thereon, a circuit means for electrically adding the respective impedance units and placing into circuit an impedance unit of value proportional to the total aircraft weight resting on the wheels, means for inserting into circuit an electrical impedance unit of value proportional to the sum of the total cargo weight to be loaded and the aircraft tare weight prior to loading, an electrical circuit responsive to the sum and total weight variable impedance units in combination to determine the difference therebetween, and operative, means controlled by such circuit for adjusting the first variable electrical impedance unit, to a value proportional to the weight of cargo yet to be loaded to a second variable electrical impedance unit and operative means for setting it to a value proportional to the moment of such cargo weight about a reference datum, and a third variable electrical impedance unit and operative means for setting it to a value dependent on the ratio of the values of the first and second impedance units; together with a selector device controlled by the latter means which is set to a position determined by the current setting of the third variable impedance unit, and a multiplicity of grouped electric circuits corresponding to plural possible sequences of consecutive compartments among which the cargo is to be distributed, of which each group comprises a number of circuits corresponding to the various numbers of compartments in the several possible loading sequences commencing with a given compartment; such selector device setting up for completion one circuit of at least one of the circuit groups, and means for selectively completing the one of such circuits thus set up which corresponds to the first of one of the possible sequences referred to, and the selected circuit controlling in conjunction with a device responsive to the cargo weight remaining unloaded an indicating compartment loading director showing the next compartment to be loaded, in correspondence with the quotient of cargo weight and a constant representing the number of compartments in the selected loading sequence. Construction.-In Figs. 1, 2, an empty aircraft divided into plural compartments adapted to receive a predetermined cargo weight is positioned with its nose wheel on a weighing scale 41 and its two main wheels on weighing scales 42, 43 to adjust corresponding resistances 46, 47 in proportion to the nose wheel weight, and resistances 52, 53, 54, with resistances 52<SP>1</SP>, 53<SP>1</SP>, 54<SP>1</SP> in proportion to the respective main wheel weights. An aircraft selector switch 58, manually operable by knob 20 in correspondence with the type of aircraft in use, having ganged sections A, B and C inserts over section A a resistance proportional to the distance between the main and nose wheels in series with resistance 69; the combination being connected in one branch of a D.C. energized Wheatstone bridge circuit B1 determining the aircraft moment about the nose wheel as loading proceeds, completed by resistances 52, 52<SP>1</SP> in series and a variable annular resistance 73 adjustable by a known rebalancing servo-system 26, 36 normally disabled by the open contacts of a relay energizable over connection 305. Resistances 46, 53 are connected in series in a similar bridge circuit B3, determining the accumulated total weight of aircraft and cargo loaded, comprising in one branch resistances 21, 22 and in the other branch resistances 46, 53, 53<SP>1</SP> in series, with rebalancing resistance 91 adjustable by a servo-system normally disabled by the open contacts of a further relay energizable over connection 305. Resistance 75 ganged for variation with resistance 73 and resistance 86 ganged for variation with resistance 91 are respectively connected in series as one branch of a bridge B2 determining the aircraft centre of gravity as loading proceeds, which is completed by resistance 80 in series with rebalancing resistance 82 adjustable by a servosystem normally disabled by open contacts of an associated relay energizable over connection 305. Resistances 47, 54, 541 are connected in series over normally open contacts 103, 109 of a relay energizable over connection 325 in one arm of a bridge B4 determining the combined aircraft and accumulated cargo weight prior to loading a compartment, whose opposite arm includes a rebalancing resistance 121, connected in circuit over normally closed contacts 114, 116 of a relay energizable over connection 350, and adjustable by a servo-system normally disabled by open contacts of an associated relay energizable over connection 325. Resistances 47, 54, 54<SP>1</SP> are also connected in series over normally open contacts 104, 111 of a relay energizable over connection 306 into one arm of a bridge B5 determining the aircraft basic weight, whose opposite arm includes a rebalancing resistance 136 connected in circuit over normally closed contacts 129, 132 of a relay energizable over connection 320 and adjustable by a servo-system normally disabled by open contacts of an associated relay energizable over connection 306. Closure of contacts 132, 134 connects resistance 136 as one arm of bridge B6 determining the cargo weight accumulated in the aircraft, in series with a rebalancing resistance 143 adjustable by a servo-system normally disabled by open contacts of an associated relay energizable over connection 320; the bridge being completed by a resistance 146 ganged for adjustment by the rebalancing servo-system of bridge B3, together with other ganged resistances 147, 148, 149. Resistance 147 is connected in one arm of bridge B7 determining the weight accumulated in each compartment, whose opposite arm comprises resistance 121 in series, over contacts 116, 118 when closed, with rebalancing resistance 174 adjustable by a servo-system normally disabled by open contacts of an associated relay energizable over connection 350; and resistance 148 is connected in series with a resistance 160, variable manually in proportion to the total cargo weight to be loaded, as one arm of bridge B8 determining the gross weight of the aircraft, which is completed over normally closed contacts 179, 182 of a relay energizable over connection 326 by a rebalancing resistance 186 adjustable by a servo-system normally disabled by open contacts of an associated relay energizable over connection 306; while resistance 149 is connected in one arm of bridge B9 determining the remaining cargo weight in series with a rebalncing resistance 231 adjustable by a servosystem normally disabled by the open contacts of an associated relay energizable over connection 326, the bridge being completed, on closure of contacts 182, 184, by the variable resistance 186 of bridge B8. A resistance 188 ganged for variation by the rebalancing servosystem of. bridge B8 is connected as one arm of bridge B10 determining the gross moment of the aircraft about the nose wheel, completed by a resistance 190 in series with a resistance corresponding to the aircraft type inserted by section B of aircraft selector switch 58, and by a rebalancing resistance 204, adjustable by a servo-system normally disabled by open contacts of an associated relay energizable over connections 306; which is also ganged to adjust a variable resistance 206, forming one arm of bridge B11 determining the remaining cargo moment about the nose wheel. The bridge is completed by resistance 222 ganged for adjustment by the rebalancing servo-system of bridge B1, in series with a rebalancing resistance 215 adjustable by a servo-system normally disabled by open contacts of an associated relay energizable over connection 326; and a variable resistance 217 ganged for adjustment by the servo-system is connected over lines 241 and 238 to variable resistance 232 adjustable by the rebalancing servo-system of the remaining cargo weight bridge B9 as one branch of a bridge B12 (Fig. 3) whose other branch comprises resistance 239 and rebalancing resistance 243 adjustable by a servo-system normally disabled by open contacts of the associated relay energizable over connection 326, to determine the ratio between the remaining cargo moment and remaining cargo weight. The rebalancing servo-system of bridge B12 is ganged to rotate a contact arm 248 of a compartment sequence selector switch 249 (which with its associated apparatus described below is multipled for differing aircraft types and selected for operation by section " C " of the aircraft selector switch 58, connecting positive battery to the appropriate contact arm 248) engaging plural concentric arcuate rows of insulated contacts, 263, 264, &c., the number of which rows correspond to the number of cargo compartments in the aircraft and the number of which contacts in each row diminishing sequentially by one per row from maximum in the outer row to minimum in the inner row. The contacts of the outer row 263 are designated C, C-D, C-E, C-F, C-G ... C-O and are connected to respective contacts 266 of each of 13 sections a to m of a multiway ganged compartment loading selector switch 267; the 12 contacts of the next inner row 264 are designated D, D-E, D-F, D-G ... D-O and are connected to respective contacts 268 of the switch sections a to l, and so on sequentially; t